Fault detection and localisation of fault or fault in a DC system with multiple DC-sources is an important skill to maintain power systems and to operate such systems optimally. However, DC systems may in reality become complex systems when assembled and during operation. The task of fault finding easily becomes complex and assumed faults and their localisation in a system may when the actual component is found and inspected turn out not to be faulty or located where expected. Likewise fault localisation may be very time consuming if not practically unfeasible or even impossible if each source is to be tested individually.
In particular, DC-systems may during installation be installed with deviations from the intended installation and faults may be introduced. Likewise a DC-system may become damaged or degenerate over time with a huge number of combinations of possible faults.
DC-systems may include Photo Voltaic (PV) systems, battery systems, fuel cell system or hybrids thereof or similar arrangements characterised in having multiple sources arranges in series.
Patent application WO2012152284 generally discloses a method for diagnosing a fault within solar cell systems including multiple solar cell modules. Part of WO2012152284 also discloses a method for fault localisation and determining the fault type. However, the fault localisation procedure requires use of additional setup including a DC BIAS. Also the method requires analysis of the measurement in a different domain (time domain reflectometry), which adds complexity to the procedure.
Prior art including the patent application WO2012152284 is also limited in a further aspect by suggesting use of systems or methods that need to be individually configured or applied. Thus, although individual faults may be detected and localized, different apparatuses or methods must be connected, disconnected or reconfigured to accomplish measurements. Thus, there is a need for a more integrated apparatus or procedure that can ease detection and localisation and even improve detection and localisation by allowing combined assessments. Hence, a single device or approach to catch a multitude of different but a-priori unknown but albeit detectable faults is desired.